Drum-type washing machine

ABSTRACT

In a drum-type washing machine, a plurality of dampers include a first damper and a second damper, the second damper is provided in such a manner that compression force on the second damper from a rotary drum rotated in the forward direction is larger than that on the first damper, the second damper and a vibration detection portion are arranged posterior to a gravity center of a water tank in the front and rear direction, and the first damper is arranged anterior to the second damper. Thus, precise imbalance determination is performed, so that low vibration is realized.

TECHNICAL FIELD

The present invention relates to a drum-type washing machine forcontrolling vibration of its entire water tank.

BACKGROUND ART

Conventionally, a configuration in this type of drum-type washingmachine is proposed that a vibration detector is provided in a watertank and an imbalance amount of a laundry (such as clothes) isdetermined by an output of the vibration detector in order to controlvibration (for example, refer to Patent Literature 1).

FIG. 6 shows a configuration diagram of the conventional drum-typewashing machine described in Patent Literature 1.

As shown in FIG. 6, a drum 101 for accommodating and rotating a laundryis rotatably arranged in a water tank 103. In a bottom part of the watertank 103, a motor 105 for driving and rotating the drum 101 is provided.In an opening part of the drum 101, a lid body 108 is openably andclosably provided. Between the water tank 103 and a housing 109, springbodies 110 are provided. By the spring bodies 110, a posture of thewater tank 103 is retained. The water tank 103 is supported by ananti-vibration damper 111 in such a manner that vibration of the watertank 103 is not transmitted to the housing 109 at the time of aspin-drying operation. In order to prevent that a user feels anxiety dueto transmission of the vibration of the water tank 103 to the housing109, a seal packing 107 is provided between a laundry inlet on a frontsurface of the water tank 103 and the housing 109.

On the front side of an upper part of the water tank 103, a vibrationdetector 106 using an acceleration sensor is arranged. In accordancewith an output of the vibration detector 106, an imbalance determiningportion 113 determines an imbalance state (unstable state) in the drum101. In a case where the imbalance state in the drum 101 is detected, acontrol portion 116 controls an action of the motor 5 and the like, sothat the vibration is controlled.

As well as shown in Patent Literature 1, a configuration that avibration detector is provided in a water tank and an imbalance amountof a laundry is determined by an output of the vibration detector isproposed in order to control vibration (for example, refer to PatentLiterature 2).

FIG. 7 is a vertical sectional view of the conventional drum-typewashing machine described in Patent Document 2. FIG. 8 is an internalfront view of major parts of the same drum-type washing machine.

As shown in FIGS. 7 and 8, a drum 121 accommodated in a water tank 120is driven and rotated taking a horizontal shaft 122 attaching to thedrum 121 as a rotation center axis. The water tank 120 is hanged downfrom an upper part of a main body 118 by two pairs of spring bodies 126.The water tank 120 is supported from a bottom part of the main body 118by a pair of anti-vibration dampers 127. In a front part of the watertank 120, a weight 128 for suppressing vibration of the water tank 120is provided. In the water tank 120, a vibration detector 130 fordetecting the vibration of the water tank 120 by utilizing anacceleration sensor is provided. As shown in FIG. 8, the vibrationdetector 130 is provided at a symmetrical position to a motor 124arranged in the vicinity of a lower corner part of the main body 118taking a center shaft 134 of the water tank 120 as a center. When thelaundry becomes imbalanced, the vibration detector 130 detects a maximumvibration value of the water tank 120 vibrated taking the heavy motor124 as a substantial revolution center.

-   Patent Literature 1: JP 2010-277 A-   Patent Literature 2: JP 6-233890 A

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, in the conventional configurations, in a case where the laundryexists so as to be leaned to the front surface side or the center sideof the rotary drum at the time of a spin-drying step, vibration on thefront surface side of the water tank becomes larger than vibration onthe back surface side of the water tank. Meanwhile, the seal packingprovided between the front surface side of the water tank and thehousing is generally made of an anti-vibration rubber material. When thevibration detector is arranged on the front side of the upper part ofthe water tank, even in a case of abnormal vibration of the water tank,the vibration is damped by an anti-vibration effect of the seal packing.Therefore, there is a problem that a vibration state of the water tankis not easily precisely detected by the vibration detector.

In a case where the laundry exists so as to be leaned to the backsurface side of the drum, the vibration of the water tank is damped bythe anti-vibration damper. Thus, a vibration value is decreased.Therefore, even when vibration components in plural directions are to bedetected by the acceleration sensor of the vibration detector arrangedon the front side of the upper part of the water tank, a determiningmethod becomes complicated. In such a way, there is also a problem thatthe imbalance state is not easily determined.

The present invention is to solve the above conventional problems, andan object thereof is to provide a low-vibration drum-type washingmachine for performing precise imbalance determination by an arrangementbalance between a support damper and an anti-vibration damper, anarrangement position and an arrangement direction of the anti-vibrationdamper, an arrangement position of an acceleration sensor, and the like.

Means to Solving the Issue

In order to solve the above conventional problems, a drum-type washingmachine of the present invention includes a rotary drum having asubstantially horizontal axis of rotation;

a water tank incorporating the rotary drum;

a motor for rotating the rotary drum;

a washing machine housing elastically-supporting the water tank fromunderneath by a plurality of dampers; and

a vibration detector for detecting vibration of the water tank,

wherein the plurality of dampers comprise a first damper and a seconddamper,

the second damper is provided in such a manner that compression force onthe second damper from the rotary drum rotating in a forward directionis larger than that on the first damper,

the second damper and the vibration detector are arranged posterior to agravity center of the water tank in a front and rear direction, and

the first damper is arranged anterior to the second damper.

Effect of the Invention

According to the drum-type washing machine of the present invention,precise imbalance determination is performed and low vibration isrealized.

BRIEF DESCRIPTION OF THE DRAWINGS

These aspects and features of the present invention will become clearfrom the following description taken in conjunction with the preferredembodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a vertical sectional view of a drum-type washing machineaccording to Embodiment 1 of the present invention;

FIG. 2 is a front view in which an interior of the drum-type washingmachine of FIG. 1 is seen;

FIG. 3 is a vertical sectional view of the drum-type washing machineaccording to a second embodiment of the present invention;

FIG. 4 is a front view in which an interior of the drum-type washingmachine of FIG. 3 is seen;

FIG. 5 is a block circuit diagram showing a part of a configurationrelating to a control device of the drum-type washing machine of FIG. 3;

FIG. 6 is a configuration diagram of a conventional drum-type washingmachine;

FIG. 7 is a vertical sectional view of another conventional drum-typewashing machine; and

FIG. 8 is a front view in which an interior of the drum-type washingmachine of FIG. 7 is seen from.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to a first aspect of the present invention, there is provideda drum-type washing machine, comprising:

a rotary drum having a substantially horizontal axis of rotation;

a water tank incorporating the rotary drum;

a motor for rotating the rotary drum;

a washing machine housing elastically-supporting the water tank fromunderneath by a plurality of dampers; and

a vibration detector for detecting vibration of the water tank,

wherein the plurality of dampers comprise a first damper and a seconddamper,

the second damper is provided in such a manner that compression force onthe second damper from the rotary drum rotating in a forward directionis larger than that on the first damper,

the second damper and the vibration detector are arranged posterior to agravity center of the water tank in a front and rear direction, and

the first damper is arranged anterior to the second damper.

According to the second aspect of the present invention, there isprovided the drum-type washing machine according to the first aspect,wherein the vibration detector and the motor are arranged symmetricallyabout the axis of rotation of the rotary drum.

According to the third aspect of the present invention, there isprovided the drum-type washing machine according to the first aspect orthe second aspect, wherein the second damper and the vibration detectorare arranged in a substantially identical perpendicular plane to aperpendicular plane including a gravity center of the motor in the frontand rear direction.

According to the forth aspect of the present invention, there isprovided the drum-type washing machine according to the first aspect orthe second aspect, further comprising a spring suspending the water tankfrom the washing machine housing, wherein:

the spring is arranged in a substantially identical perpendicular planeto a perpendicular plane including the gravity center of the water tankin the front and rear direction.

Before the description of the present invention proceeds, it is to benoted that like parts are designated by like reference numeralsthroughout the accompanying drawings. Hereinbelow, embodiments of thepresent invention will be described with reference to the accompanyingdrawings.

Embodiment 1

FIG. 1 is a vertical sectional view of a drum-type washing machineaccording to Embodiment 1 of the present invention. FIG. 2 is a frontview in which an interior of the same drum-type washing machine is seen.

As shown in FIGS. 1 and 2, a rotary drum 17 formed in a cylindricalshape with a bottom is rotatably arranged in a water tank 19. In otherwords, the water tank 19 accommodates (incorporates) the rotary drum 17.On the entire surface of an outer peripheral wall of the rotary drum 17,a large number of water passage holes 18 are provided. In a rotationcenter of the rotary drum 17, an axis of rotation (rotation center axis)20 exists. The axis of rotation 20 is substantially horizontal, and theaxial direction of the rotary drum 17 is also substantially horizontal.A drum pulley 28 is coupled to a back surface of the water tank 19positioned on the axis of rotation 20. The drum pulley 28 is connectedto a motor 21 via a belt 29. The motor 21 is coupled to the rotary drum17 by the belt 29 and the drum pulley 28. The motor 21 drives androtates the rotary drum 17 in the forward direction or the reversedirection. On an inner wall surface of the rotary drum 17, a pluralityof protuberances 22 for agitating a laundry is provided.

A water tank unit 37 is configured by the rotary drum 17, the water tank19, the motor 21, the drum pulley 28, and the like.

As shown in FIG. 2, weight of the water tank 19 is supported by dampingand anti-vibration dampers 25 and 26 attached to a base bottom portion24 of a washing machine housing 23. Spring bodies 27 are providedbetween an upper surface of the washing machine housing 23 and an upperpart of the water tank 19. The water tank 19 is oscillatably andelastically anti-vibration supported by the spring bodies 27. That is,the washing machine housing 23 elastically supports the water tank 19from the lower side by the plurality of dampers 25 and 26.

As shown in FIG. 2, the dampers 25 and 26 include a pair of supportdampers 25 (first dampers) left-right symmetrically arranged when seenfrom the front side, and one anti-vibration damper 26 (a second damper).

The support dampers 25 support the water tank 19 and suppress vibrationof the water tank 19. As shown in FIG. 1, the support dampers 25 arearranged on the more front surface side than (anterior to) a gravitycenter position G of the water tank unit 37 in the front and rear(front-back) direction.

The anti-vibration damper 26 particularly suppresses the vibration ofthe water tank 19. As shown in FIG. 1, the anti-vibration damper 26 isarranged on the more back surface side than (posterior to) the gravitycenter position G. That is, the support dampers 25 are arranged on themore front surface side than the anti-vibration damper 26. The watertank unit 37 is supported by the support dampers 25 and theanti-vibration damper 26 in a favorably balanced state, so that dampingand anti-vibration are performed.

As shown in FIG. 2, the anti-vibration damper 26 is provided in such amanner that compression force on the anti-vibration damper 26 from therotary drum 17 rotated in the forward direction (counterclockwiserotation) A is larger than that on the two support dampers 25. In otherwords, when seen from a front, the anti-vibration damper 26 is providedin such a manner that a straight line connecting a housing supportportion 35 and a water tank support portion 36 is inclined at an angleof α to the upstream side of the forward direction A with respect to astraight line connecting the housing support portion 35 and a centerposition C of the water tank 19.

It should be noted that in a case where the forward direction and thereverse direction of the rotary drum 17 at the time of a spin-dryingstep are set to be opposite to each other (that is, in a case where theforward direction of the rotary drum 17 is clockwise when seen from thefront), the anti-vibration damper 26 may be arranged at a left-rightsymmetrical position when seen from the front (that is, in a lower parton the left side).

The anti-vibration damper 26 is provided in such a manner that aninclination angle of the anti-vibration damper 26 with respect to abottom surface of the washing machine housing 23 extending in thehorizontal direction becomes smaller than that of the support dampers25. Thereby, the anti-vibration damper 26 particularly exerts a largerdamping effect on vibration in the horizontal direction (left and rightdirection of FIG. 2).

It should be noted that damping force of the support dampers 25 and theanti-vibration damper 26 may be the same. Alternatively, damping forceof the anti-vibration damper 26 may be slightly weaker than that of thesupport dampers 25.

As shown in FIG. 1, a seal packing 38 formed of a rubber material or thelike is coupled between the front surface side of the water tank 19 andthe washing machine housing 23. An opening portion 39 of the washingmachine housing 23 is openably and closably covered by a lid body 30. Byopening the lid body 30, the laundry can be brought into the rotary drum17 through the opening portion 39 and taken out from the rotary drum 17.

As shown in FIG. 1, a control device 31 is provided on the upper side ofthe water tank 19. The control device 31 is configured by a microcomputer or the like for controlling a series of steps such as washing,rinsing, and spin-drying, and the like. The control device 31 transmitssignals with an input setting portion 32 arranged on the upper side ofthe lid body 30 and an acceleration sensor (vibration detector) 34arranged in the upper part of the water tank 19. The control device 31also controls rotation and the like of the motor 21.

The acceleration sensor 34 detects acceleration and vibration not onlyin one direction but also in multiaxis (two or three axis) directionssuch as the front and rear direction, the left and right direction, andthe up and down direction. Actual vibration of the water tank unit 37 isnot always limited to one direction. Thus, by using the multiaxisacceleration sensor 34, movement of the water tank unit 37 is detectedwith high precision.

Actions and operations of the drum-type washing machine configured asabove will be described.

The lid body 30 is opened and the laundry is brought into the rotarydrum 17, so that an operation is started. In a first washing step, therotary drum 17 is driven and rotated at low speed by the motor 21. Bydriving and rotating the rotary drum 17, the laundry in the rotary drum17 is brought up and dropped onto a water surface in the rotary drum 17.By such an action, the washing step is progressed. After the washingstep is performed for a predetermined time, washing water in the watertank 19 is drained, and intermediate spin-drying is performed. Afterthat, a rinsing step is performed. Also in the rinsing step, the sameaction as the washing step is performed. In the spin-drying step, bydriving and rotating the rotary drum 17 at high speed, water iscentrifugally removed from the laundry.

In a case where the laundry brought in the rotary drum 17 is leaned toone side at the time of the spin-drying step, rotation for spin-dryingis preferably performed while absorbing leaning (bias) of the laundry.In order to do so, by oscillatably anti-vibration supporting the watertank 19 by the spring bodies 27 or the like, the vibration is preventedfrom being transmitted to the washing machine housing 23. However, in acase where the leaning of the laundry is abnormally large, the watertank 19 is abnormally vibrated. Thus, there is a fear that large noiseis generated from the washing machine or in the worst case, the washingmachine is damaged.

In the first embodiment, the control device 31 controls rotation inaccordance with the vibration of the water tank unit 37 in the multiaxisdirections detected by the acceleration sensor 34. The control device 31lowers the rotation number of the motor 21, and stops a spin-dryingaction of the rotary drum 17 and supplies the water again. In such away, in accordance with a determination result of the vibration, theactions such as easing the leaning of the laundry are performed bycontrol of the control device 31.

The acceleration sensor 34 is provided on the more back surface sidethan the gravity center position G of the water tank unit 37. Thus, evenwhen the leaning of the laundry is generated in any place in the rotarydrum 17, there is little influence on the acceleration sensor 34 bydamping of the seal packing 38. Therefore, the vibration of the watertank unit 37 is determined with favorable precision, so that highlyprecise vibration detection is realized.

Further, by an arrangement position of the anti-vibration damper 26, thevibration of the rotary drum 17 in the left and right direction inparticular is largely damped. Thus, a magnitude of the vibration isdetermined based on the vibration of the water tank unit 37 mainly inthe up and down direction. In such a way, an easier detection method isrealized.

It should be noted that a case where the axial direction (axis ofrotation 20) of the rotary drum 17 is arranged substantiallyhorizontally from the front surface side toward the back surface side isdescribed in the first embodiment. However, the axial direction may beinclined from a horizontal line.

As described above, in the first embodiment, the support dampers 25, theanti-vibration damper 26, and the acceleration sensor 34 are arranged ina favorably balanced manner relative to the water tank unit 37. Thus,precise and efficient imbalance determination is performed irrespectiveof a place of the leaning of the laundry. By the determination resultthereof, low-vibration and low-noise spin-drying control is performed.

The anti-vibration damper is provided at the position and in thedirection so that the compression force on the anti-vibration damperacts in the rotation direction (forward direction A) of the rotary drum17. Thus, the vibration of the water tank in the left and rightdirection is efficiently damped.

Further, the arrangement position of the anti-vibration damper 26 in theup and down direction relative to the water tank unit 37 is on the morebottom surface side than the support dampers. Thus, the vibration of thewater tank 19 in the left and right direction is more effectivelysuppressed.

As described above, in the drum-type washing machine according to thefirst embodiment, by an arrangement balance between the support dampersand the anti-vibration damper, the arrangement position and thedirection of the anti-vibration damper, an arrangement position of theacceleration sensor, and the like, low vibration and low noise can berealized. Therefore, the drum-type washing machine according to thefirst embodiment can be applied to a use for other washing machines andthe like having a spin-drying function.

Second Embodiment

FIG. 3 is a vertical sectional view of the drum-type washing machine ina second embodiment of the present invention. FIG. 4 is a front view inwhich an interior of the drum-type washing machine of FIG. 3 is seen.

As shown in FIGS. 3 and 4, a water tank unit 49 is provided in aninterior of a washing machine housing 41. The water tank unit 49includes a water tank 42, a rotary drum 43, and a motor 45. The watertank 42 is oscillatably arranged in the interior of the washing machinehousing 41. The rotary drum 43 is rotatably arranged in the water tank42. A axis of rotation (rotation center axis) 44 extending in thehorizontal direction is provided in a rotation center part of the rotarydrum 43. The motor 45 arranged in the vicinity of the back surface sideof the water tank 42 is coupled to the axis of rotation 44 via a belt46. By this motor 45, the rotary drum 43 is driven and rotated in theforward direction or in the reverse direction. On an inner wall surfaceof the rotary drum 43, a plurality of protuberances 47 for agitating thelaundry is provided. On an outer peripheral wall of the rotary drum 43,a large number of water passage holes 48 are provided.

The water tank 42 is supported by two support dampers 51 and oneanti-vibration damper 91 attached to a lower part of the washing machinehousing 41. As shown in FIGS. 3 and 4, a plurality of spring bodies 50is provided between an upper part of the washing machine housing 41 andthe water tank 42. The spring bodies 50 hang down (suspend) the watertank 42 from the washing machine housing 41. The water tank 42 isoscillatably anti-vibration supported by the plurality of spring bodies50.

As shown in FIG. 3, the pair of spring bodies 50 is arranged on asubstantially identical perpendicular plane to a perpendicular planeincluding a gravity center position Gs of the water tank unit 49 in thefront and rear direction.

The two support dampers 51 are dampers provided for a purpose ofsupporting the water tank 42 and suppressing vibration of the water tank42. As shown in FIG. 4, the two support dampers 51 are left-rightsymmetrically arranged when seen from the front. As shown in FIG. 3, thetwo support dampers 51 are arranged on the more front surface side thanthe gravity center position Gs of the water tank unit 49. Theanti-vibration damper 91 is a damper provided for a purpose of mainlysuppressing the vibration of the water tank 42. As shown in FIG. 3, theanti-vibration damper 91 is arranged on the more back surface side thanthe gravity center position Gs. The anti-vibration damper 91 isconnected to the washing machine housing 41 at a housing support portion93 and connected to the water tank 42 at a water tank support portion94. It should be noted that the anti-vibration damper 91 may beindirectly connected to the washing machine housing 41 and the watertank support portion 94 via other members. The water tank 42 issupported by the respective dampers in a favorably balanced manner, sothat the damping and the anti-vibration of the water tank 42 areperformed.

It should be noted that in the second embodiment, friction dampers areused as the dampers 51 and 91. In an interior of the friction damper, afriction pad (not shown) is accommodated. Friction force is generated byrubbing this friction pad and a tube (not shown), and the friction forceserves as damping force for suppressing the vibration of the water tank42.

As shown in FIG. 4, the anti-vibration damper 91 is provided in such amanner that compression force on the anti-vibration damper 91 from therotary drum 43 rotated in the forward direction (counterclockwiserotation) A is larger than that on the two support dampers 51. In otherwords, when seen from the front, the anti-vibration damper 91 isprovided in such a manner that a straight line connecting the housingsupport portion 93 and the water tank support portion 94 is inclined atan angle of α to the upstream side of the forward direction A withrespect to a straight line connecting the housing support portion 93 anda center position C of the water tank 42.

As shown in FIG. 4, the anti-vibration damper 91 is provided in such amanner that an inclination angle of the anti-vibration damper 91 withrespect to a bottom surface of the washing machine housing 41 extendingin the horizontal direction becomes smaller than that of the supportdampers 51. Thereby, the anti-vibration damper 91 particularly exerts alarger damping effect on the vibration in the horizontal direction (leftand right direction of FIG. 4).

It should be noted that damping force of the support dampers 51 and theanti-vibration damper 91 may be the same. Alternatively, the dampingforce of the anti-vibration damper 91 may be slightly weaker than thedamping force of the support dampers 51.

As shown in FIG. 3, a vibration detector 78 is arranged in an upper parton the rear surface side of the water tank 42. As shown in FIG. 4, thevibration detector 78 is arranged at a substantially symmetricalposition to the motor 45 with respect to the axis of rotation (rotationcenter axis) 44. The vibration detector 78 utilizing an accelerationsensor for detecting vibration of the water tank unit 49 detects notonly acceleration in one direction but also vibration in thethree-dimensional directions of the front and rear direction (X axisdirection), the left and right direction (Y axis direction), and the upand down direction (Z axis direction). Based on a detection result ofthe vibration by the vibration detector 78, an operation is controlled.Actual vibration of the water tank unit 49 is not always limited to onedirection. Thus, by using the multiaxis acceleration sensor, thevibration is detected with high precision.

As shown in FIG. 3, the vibration detector 78, a gravity center positionGm of the motor 45, and the anti-vibration damper 91 are arranged on asubstantially identical perpendicular plane in the front and reardirection.

A housing opening portion is provided at a position facing a laundryoutlet/inlet 53 of the rotary drum 43 in the washing machine housing 41.A lid body 52 is provided so as to openably and closably cover thishousing opening portion. By opening the lid body 52, the laundry can betaken out and brought into the rotary drum 43 through the laundryoutlet/inlet 53. A front part of the water tank 42 and the housingopening portion are coupled by a seal packing 92. The seal packing 92 isprovided so as to suppress the vibration of the water tank unit 49 andto watertightly seal in such a manner that water does not come into aspace between the washing machine housing 41 and the water tank 42. Whenthe lid body 52 is closed, the lid body 52 and the seal packing 92 areclosely attached, so that the washing machine housing 41 is sealed.

A control device 81 is provided in an upper part in the washing machinehousing 41. The control device 81 is configured by a micro computer orthe like. In accordance with mode setting and a control program, thecontrol device 81 controls the motor 45, a first electromagnetic valve57, a second electromagnetic valve 58, a drainage pump 63, and acirculation pump 67, so as to execute cleaning steps including a washingstep, a rinsing step, and a spin-drying step.

In the interior of the washing machine housing 41, a water supplypassage 54 for supplying washing water (such as tap water) into thewater tank 42, a drainage passage 55 for draining the washing water inthe water tank 42 to an exterior of the washing machine housing 41, anda water circulation passage 56 for circulating the washing water in thewater tank 42 are provided.

The water supply passage 54 is configured by a first water supply hose59, a second water supply hose 60, a detergent accommodating portion 61,and a water supply passage 62.

The first electromagnetic valve 57 is provided in the first water supplyhose 59. The second electromagnetic valve 58 is provided in the secondwater supply hose 60. The detergent accommodating portion 61accommodates a drawer (not shown) storing detergent and softener in sucha manner that the drawer can be pulled out by touch from the exterior.By opening the first electromagnetic valve 57 or the secondelectromagnetic valve 58, the washing water flows into the first watersupply hose 59 or the second water supply hose 60. The washing waterflowing into the first water supply hose 59 or the second water supplyhose 60 passes through the detergent accommodating portion 61 and thewater supply passage 62, and is supplied into the water tank 42.

The drainage passage 55 is configured by a drainage tube 64, a filtercase 88, the drainage pump 63, and a drainage hose 66.

The drainage tube 64 is connected to a drainage port 95 provided in arecessed portion 71 in a bottom part of the water tank 42 and connectedto the filter case 88. In an interior of the filter case 88, a lintfilter 65 for collecting lint in the washing water is provided. The lintfilter 65 is configured so as to be detached by pulling outwardly afilter grip 89 provided in a lower part on a front surface of thewashing machine housing 41.

The drainage pump 63 is connected to the filter case 88 and the drainagehose 66. The drainage hose 66 is provided so as to extend upward in theexterior of the washing machine housing 41 from the interior of thewashing machine housing 41. By driving the drainage pump 63 at apredetermined timing such as a time of finishing the washing step and atime of finishing the rinsing step, the washing water in the water tank42 passes through the drainage tube 64, the filter case 88, the drainagepump 63, and the drainage hose 66 in this order, and is drained to theexterior.

It should be noted that in the second embodiment, the filter case 88 isarranged in a right lower part on the front surface of the washingmachine housing 41 in order to improve handleability of the filter grip89. In the second embodiment, the drainage port 95 is provided on themore right side than a horizontal center of the water tank 42 when seenfrom the front in order to efficiently arrange the drainage tube 64.

The water circulation passage 56 is provided so as to circulate thewashing water in the water tank 42 at a predetermined timing such as atime of a pre-washing step, the time of the washing step, and the timeof the rinsing step. By this water circulation passage 56, the detergentcan be quickly dissolved into the washing water, and imbalance of thedetergent is prevented. As a result, washing and rinsing abilities ofthe drum-type washing machine are improved.

This water circulation passage 56 is configured by the drainage tube 64,the filter case 88, an inflow side passage 68, the circulation pump 67,a discharge side passage 69, and jet ports 70. The inflow side passage68 is a passage connecting the filter case 88 and the circulation pump67. The discharge side passage 69 is a passage connecting thecirculation pump 67 and the jet ports 70. The jet ports 70 are providedin the front part of the water tank 42 so as to discharge the washingwater passing through the discharge side passage 69 into the rotary drum43.

By driving the circulation pump 67, the washing water in the water tank42 passes through the drainage tube 64, the filter case 88, the inflowside passage 68, the circulation pump 67, the discharge side passage 69,and the jet ports 70 in this order, and is discharged into the rotarydrum 43 as circulated water shown by a solid arrow. It should be notedthat the plurality of jet ports 70 is provided in line in thecircumferential direction of the rotary drum 43. Thereby, the circulatedwater is sprinkled toward the laundry in the rotary drum 43 from pluraldirections.

A heater 72 including a sheathed heater or the like is provided in therecessed portion 71 formed in the bottom part of the water tank 42 andconnected to the drainage tube 64 in order to heat the washing water.The heater 72 is arranged in such a manner that the longitudinaldirection thereof matches or substantially matches with the horizontaldirection. By this heater 72, the washing water in the water tank 42 isheated.

The washing water heated by the heater 72 is circulated via the watercirculation passage 56, discharged into the rotary drum 43, andsprinkled on the laundry. After that, the washing water sprinkled on thelaundry is moved into the water tank 42 through the water passage holes48 and heated by the heater 72. These actions are repeated. By heatingthe washing water, molecule activities of the washing water areactivated, and the detergent is activated. As a result, a washingability of the washing water is improved, so that washing non-uniformityof the laundry can be reduced. In the vicinity of the heater 72, atemperature detector 73 for detecting a water temperature such as athermistor is provided.

An air trap 74 is formed in a side wall on the rear side of the bottompart of the water tank 42 so as to communicate with the drainage tube64. The air trap 74 is connected to an air tube 75. The air tube 75 isconnected to a water level detector 76 provided in the upper part in thewashing machine housing 41. The water level detector 76 is configured byfor example a pressure sensor or the like. The water level detector 76detects a water level of the washing water in the water tank 42 based onwater pressure of the washing water in the interior of the water tank42, that is, pressure in the corresponding air trap 74.

In the upper part in the washing machine housing 41, a coupling hose 77for coupling an upper part on a rear surface of the detergentaccommodating portion 61 and the upper part of the water tank 42 isprovided. The coupling hose 77 functions to remove the air in the watertank 42 pressurized during the washing steps.

An operation display portion 79 is provided in the upper part on thefront surface of the washing machine housing 41. In the operationdisplay portion 79, an input setting portion 80 to which modes such asan operation course and various functions can be set (selected), and adisplay portion 96 (refer to FIG. 5) for displaying information inputtedto the input setting portion 80 are provided. A user can set the modessuch as the operation course and the various functions by inputting tothe input setting portion 80.

FIG. 5 is a block circuit diagram showing a part of a configurationrelating to the control device of the drum-type washing machine in theembodiment of the present invention.

As shown in FIG. 5, the control device 81 includes a control portion 82and a load drive portion 86. When a power switch 84 is turned on,electric power is supplied from a commercial power source 83, and thecontrol portion 82 starts controlling each portion. The control portion82 controls the load drive portion 86 based on output signals of thewater level detector 76, the temperature detector 73, a cloth amountdetector 85, the vibration detector 78, and a rotation speed detector90. The load drive portion 86 is configured by a bidirectionalthyristor, a relay, or the like. Upon control by the control portion 82,the load drive portion 86 activates the motor 45, the heater 72, thefirst electromagnetic valve 57, the second electromagnetic valve 58, thedrainage pump 63, the circulation pump 67, and the like. Thereby, thewashing step, the rinsing step, and the spin-drying step are performed.It should be noted that the cloth amount detector 85 is to detect anamount of the laundry in the rotary drum 43. A notification portion 87is to display information to be given to the user. The rotation speeddetector 90 detects rotation speed of the rotary drum 43 by detectingthe rotation number of the rotary drum 43 per unit time.

Actions and operations of the drum-type washing machine configured asabove will be described.

In the spin-drying step, in general, the vibration of the water tank 42is anti-vibration damped in a favorably balanced manner by one pair ofspring bodies 50, one pair of support dampers 51, one anti-vibrationdamper 91, weights provided in each part in the water tank unit 49 (notshown), and the like.

However, particularly when water is removed from a small amount oflaundry and an imbalance state is detected, the laundry is easilygathered in a mass in a rear part of the rotary drum 43 because anoperation of the protuberances 47 in the rotary drum 43 also exertinfluence. Meanwhile, the support dampers 51 are arranged on the morefront side than a gravity center of the water tank unit 49, and thespring bodies 50 are arranged on the substantially identicalperpendicular plane to the perpendicular plane including the gravitycenter of the water tank unit 49 in the front and rear direction. Whenthe amount of the laundry is small, weight of the water tank unit 49 isdecreased. Therefore, an anti-vibration property of the seal packing 92effectively acts on the front surface side of the water tank 42, so thatthe rear surface side of the water tank 42 is largely vibrated.

On the rear surface side of the bottom part of the water tank 42, theheavy motor 45 is attached to a left lower part when seen from thefront. Thus, the water tank 42 is to be vibrated taking the motor 45 asa substantial revolution center. In a case of a small amount of laundry,the laundry is easily brought up at once to the right upper side whenseen from the front by the rotary drum 43. Therefore, the water tank 42is largely vibrated from the right upper direction to the left upperdirection when seen from the front.

As described above, the rear surface side of the water tank 42 islargely vibrated, and the water tank is largely vibrated from the rightupper direction to the left upper direction when seen from the front.With respect to such two movements of the water tank 42, the vibrationdetector 78 is provided at the substantially symmetrical position to themotor 45 when seen from the front, and arranged on a substantiallyidentical perpendicular plane to a perpendicular plane including thegravity center position Gm of the motor 45 in the front and reardirection. Therefore, the vibration detector 78 detects a maximumvibration value, so that the imbalance state of the water tank unit 49can be detected with favorable precision. After being largely vibratedfrom the right upper direction to the left upper direction when seenfrom the front, the water tank 42 is vibrated from the left lowerdirection to the right lower direction. With respect to such a watertank 42, the anti-vibration damper 91 is arranged on the substantiallyidentical perpendicular plane to the perpendicular plane including thegravity center position Gm of the motor 45 in the front and reardirection. When seen from the front, the anti-vibration damper 91 isprovided in such a manner that the straight line connecting the housingsupport portion 93 and the water tank support portion 94 is inclined atthe angle of α to the upstream side of the forward direction A withrespect to the straight line connecting the housing support portion 93and the center position C of the water tank 42. Thereby, the compressionforce effectively acts on the anti-vibration damper 91. Thus, thevibration of the water tank unit 49 in the up and down direction and theleft and right direction is efficiently damped.

As described above, in the second embodiment, the anti-vibration damperand the vibration detector are arranged on the more back surface sidethan a gravity center of the water tank in the front and rear direction,the support dampers are arranged on the more front surface side than theanti-vibration damper, and the vibration detector and the anti-vibrationdamper are arranged on the substantially identical perpendicular planeto the perpendicular plane including a gravity center of the motor inthe front and rear direction. Thereby, particularly when water isremoved from a small amount of laundry, the vibration is detected withfavorable precision, so that the spin-drying rotation is controlled. Thevibration is suppressed in such a way. Thus, a situation thatspin-drying cannot be started due to an imbalance state and the stepsare stopped in the middle is eliminated. Therefore, the steps areprogressed till the end.

As described above, the drum-type washing machine according to thesecond embodiment can suppress the vibration by detecting the vibrationwith favorable precision and controlling the spin-drying rotation.Therefore, the drum-type washing machine according to the secondembodiment can be applied to a use for other washing machines and thelike having the spin-drying function.

It is to be noted that, by properly combining the arbitrary embodimentsof the aforementioned various embodiments, the effects possessed by themcan be produced.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

The entire disclosure of Japanese Patent Application No. 2011-036733filed on Feb. 23, 2011 and Japanese Patent Application No. 2011-036756filed on Feb. 23, 2011, including specification, drawings, and claimsare incorporated herein by reference in its entirety.

1. A drum-type washing machine, comprising: a rotary drum having asubstantially horizontal axis of rotation; a water tank incorporatingthe rotary drum; a motor for rotating the rotary drum; a washing machinehousing elastically-supporting the water tank from underneath by aplurality of dampers; and a vibration detector for detecting vibrationof the water tank, wherein the plurality of dampers comprise a firstdamper and a second damper, the second damper is provided in such amanner that compression force on the second damper from the rotary drumrotating in a forward direction is larger than that on the first damper,the second damper and the vibration detector are arranged posterior to agravity center of the water tank in a front and rear direction, and thefirst damper is arranged anterior to the second damper.
 2. The drum-typewashing machine according to claim 1, wherein: the second damper and thevibration detector are arranged in a substantially identicalperpendicular plane to a perpendicular plane including a gravity centerof the motor in the front and rear direction.
 3. The drum-type washingmachine according to claim 1, wherein: the vibration detector and themotor are arranged symmetrically about the axis of rotation of therotary drum.
 4. The drum-type washing machine according to claim 1,further comprising a spring suspending the water tank from the washingmachine housing, wherein: the spring is arranged in a substantiallyidentical perpendicular plane to a perpendicular plane including thegravity center of the water tank in the front and rear direction.
 5. Thedrum-type washing machine according to claim 2, wherein: the vibrationdetector and the motor are arranged symmetrically about the axis ofrotation of the rotary drum.
 6. The drum-type washing machine accordingto claim 2, further comprising a spring suspending the water tank fromthe washing machine housing, wherein: the spring is arranged in asubstantially identical perpendicular plane to a perpendicular planeincluding the gravity center of the water tank in the front and reardirection.